Neural Precursors of Language in Infants at High Risk for Autism Spectrum Disorder

Autism spectrum disorder (ASD) is a developmental disorder characterized by difficulties in social interaction and communication. Abnormal language development is a pervasive symptom of this disorder, though research has repeatedly shown that children with ASD who develop stronger language abilities have more positive outcomes. One strategy for improving the language, and thus life experiences, of children with ASD, is to get children at risk for the disorder into effective and appropriately targeted educational interventions in the very earliest stages of life, when precursors of language and other social behaviors are developing. However, ASD is currently not diagnosed until children have reached 2 or 3 years. In this dissertation, I investigate neural predictors of later language abilities, which may be measurable before behavioral precursors to language and ASD risk emerge. In my first study, I identify neural correlates of early language development in 3-month-old infant siblings of children with ASD, who are thus at high risk of developing the disorder. I find that whereas low-risk infants showed initial neural activation that decreased over exposure to repetition-based language stimuli, potentially indicating a habituation response to repetition in speech, infants at high risk for autism (HRA) showed no changes in their neural activity to these stimuli over exposure. These results suggest that putative precursors of language acquisition are disrupted in children at high risk for ASD as young as 3 months old. In my second study, I examine whether neural correlates of language development in 3-month-old infant siblings of children with ASD predict their 18-month social and communicative outcomes. These analyses revealed that neural activity to language stimuli in 3 month olds predicted expressive and receptive language, early gestures, sentence complexity, sentence length, and autism symptomatology in 18 month olds. In many cases, these associations differed for males and females, and for high and low risk children. The current research thus identifies early putative markers of language disability and ASD symptomatology, which, with future research and educational application, may aid in determining which children are most likely to benefit from placement into language-based educational intervention programs from the very first months of life